This invention relates to a soil mixing apparatus, and more particularly to an apparatus for continuously mixing different soils primarily for nursery stock.
Soil mixing devices for nursery stock are known in the art. One conventional soil mixing apparatus incorporates a plurality of feed hoppers, each feed hopper adapted to receive a soil of different composition from the other feed hoppers. Each hopper includes an elongated feed belt in its bottom portion to discharge the soil from that particular hopper. The hoppers and their feed belts are independently mounted above an elongated conveyor belt for carrying the layers of soil from the feed hoppers to a mixing chamber. Only a single agitator is included in the first or leading feed hopper for agitating the denser soil. Thus, if the conventional apparatus utilized three feed hoppers for three different soils, four conveyor belts were required, one feed belt for each hopper and the elongated underlying conveyor belt. Not only are feed belts expensive, but each feed belt occupies the bottom portion of the hopper, which might otherwise be utilized for containing additional soil.
A popular prior art method of mixing soils for plant stock is "batch mixing", which involves depositing all the soils within a single large hopper and agitating and mixing the soils within the hopper. In batch mixing, more labor is required in order to both measure and introduce the different soils into the single hopper. Furthermore, in batch mixing, there is a tendency for the soil particles to break down and loose their integrity, thereby reducing the porosity and moisture-holding capacity of the soils. The mixer blades in batch mixing tend to break down the long fibers of peat moss, which assist in holding the soil materials and moisture around the plant. Moreover, batch mixing tends to rupture and remove the coating from the time-release fertilizer pellets included in the soil mixture.
Furthermore, in batch mixing, the operation is not continuous because the mixed soil cannot be conveyed to its next destination while the soil is being introduced into the hopper, agitated, and mixed. Thus, the feeding of the soil in the batch mixing process is intermittent.